manstey wrote:
> Is there a clever way to see if two strings of the same length vary by
> only one character, and what the character is in both strings.
>
> E.g. str1=yaqtil str2=yaqtel
>
> they differ at str1[4] and the difference is ('i','e')
>
> But if there was str1=yiqtol and str2=yaqtel, I am not interested.
>
> can anyone suggest a simple way to do this?
>
> My next problem is, I have a list of 300,000+ words and I want to find
> every pair of such strings. I thought I would first sort on length of
> string, but how do I iterate through the following:
Not sure if it can handle 300000 words, but here is something to play with.
import sys
def find_similars(words, lookup=None, dupes=None):
if lookup is None:
lookup = {}
if dupes is None:
dupes = set()
for word in words:
low_word = word.lower()
if low_word not in dupes:
dupes.add(low_word)
last = None
for i, c in enumerate(low_word):
if c == last: continue
key = low_word[:i], low_word[i+1:]
if key in lookup:
lookup[key].append(word)
else:
lookup[key] = [word]
last = c
return (group for group in lookup.itervalues() if len(group) > 1)
def main():
import optparse
parser = optparse.OptionParser()
parser.usage += " infile[s]"
parser.add_option("-n", "--limit", type="int", help="process at most
LIMIT words")
options, args = parser.parse_args()
if args:
words = (w.strip() for fn in args for w in open(fn))
else:
words = (w.strip() for w in sys.stdin)
if options.limit is not None:
from itertools import islice
words = islice(words, max_len)
for group in find_similars(words):
print " ".join(sorted(group))
if __name__ == "__main__":
main()
Peter
--
http://mail.python.org/mailman/listinfo/python-list
